Characterization and use of functionalized carbon nanotubes for the adsorption of heavy metal anions

Carbon nanotubes (CNTs) have been chemically functionalized with various oxygen-containing surface groups. The feature of abundant oxygen-containing surface functional groups on the functionalized CNTs is characterized by X-ray photoelectron spectroscopy and temperature-programmed desorption analyslis. Results indicate that the functionalized CNTs have a superior adsorption capacity toward anionic chromate CrO₄^2-, a typical toxic heavy metal ion in waste water, as compared with the unmodified ones. The excellent adsorption ability of CrO₄^2- is attributed to the interaction of CrO₄^2- with the surface oxygen-containing functional groups on the modified CNTs. The functionalized CNTs can be potentially used as an alternatively viable and promising adsorbent for the removal of heavy metal anions in waste water.